Abstract
Understanding the time-dependence of thermal evolution and recovery of displacement damage is of great significance for evaluations of material performance in harsh fusion environments. In this study, the long-time thermal evolution of irradiation-induced defects has been investigated in heavy-ion irradiated tungsten at doses above the saturation limit. Polycrystalline tungsten samples were irradiated with 6 MeV copper ions up to 0.6 dpa at room temperature, followed by a series of isothermal annealing experiments at 653 and 1123 K for 5000, 10000 and 20000 s, respectively. Annealing at both temperatures triggered the coevolution of interstitial and vacancy defects, causing changes in defect morphology, size and population statistics. The damage microstructure remained stable after 5000 s at 653 K. Subtle variations in defect density and size were found, indicating the quasi-thermal-equilibrium state of the damage microstructure. In this temperature regime, small defect clusters were depleted via annihilation and absorption, while large defect clusters and defect-impurity complexes were pinned by traps requiring further thermal activation. Pronounced time-dependence in defect evolution was found at 1123 K. Defect recovery and defect coarsening became more prominent with increasing duration. Almost all dislocation networks dissociated into individual dislocation lines after 20000 s, while nano-sized voids and loops became fewer but gained an increase in size. These findings can be attributed to the collective impact of the increasing mobility of small vacancy clusters, the continual dissociation of large vacancy clusters and small voids, and the thermally activated detrapping of defect clusters from impurities and/or other traps.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.